Liquid crystal display devices are now being widely used in a TV, a monitor for personal computers, and the like, because they are display devices with low electrical power consumption and can be reduced in weight and thickness. The liquid crystal display devices are non-self-emitting display devices and include a liquid crystal display panel containing liquid crystal molecules interposed between a pair of substrates (an active matrix substrate and a color filter substrate) and a back light. Such liquid crystal display devices display images using light from the back light by electrically controlling alignment of the liquid crystal molecules, thereby adjusting the light amount.
Such liquid crystal display devices include an alignment film on a liquid crystal layer-side surface of the liquid crystal display panel and this film regulates an alignment direction of liquid crystal molecules. This alignment film is usually subjected to an alignment treatment. The alignment treatment is made, for example, by rubbing, photo-alignment, and the like. According to the rubbing, an alignment film surface is rubbed with a cloth wound on a roller. In this technique, dusts such as a fiber of the cloth and rubbed scrapes are generated, and further, static electricity generated due to the fiber of the cloth might cause defects such as malfunction, a change in characteristics, and deterioration, of switching elements.
In the photo-alignment, a photo-alignment film is used as a material for the alignment film, and the photo-alignment film is exposed to light such as UV light, and thereby the photo-alignment film is provided with an alignment regulating force and/or an alignment regulating direction of the photo-alignment film is changed. Thus, in this technique, the alignment film can be subjected to the alignment treatment in a contact-less manner. Therefore, soils, dusts, and the like that are generated by the alignment treatment can be reduced. Further, use of this photo-alignment technique allows photo-irradiation to the alignment film in desired regions under various conditions when the photo-irradiation is performed through a pattern photomask including transmissive parts formed in a desired pattern. Thus, the photo-alignment process easily enables for each pixel to be divided into two or more domains different in alignment (tilt) direction of liquid crystal molecules, and further such domains can be easily formed into a desired shape.
Liquid crystal display panels typically have a display region where images are displayed and a frame region therearound not contributing to display. In this frame region, a light-shielding layer is usually arranged to shield light from a backlight. A resin black matrix (BM), which is formed in a color filter substrate, is usually used as the light-shielding layer.
Such a BM now needs to have a very small thickness in order for liquid crystal display devices to show a higher response rate by decreasing a distance (cell thickness) between the substrates. As a result, a transmittance of light that passes through the BM is increased, which causes light leakage from the frame region. This light leakage might have adverse effects on images displayed in the display region. Accordingly, such a conventional liquid crystal display device has room for improvement in display qualities in the vicinity of the frame region.
Patent Document 1, for example, disclosed that a light shield device is arranged between drawing wirings formed in a frame region in order to suppress generation of light leakage from an end of a display region.
[Patent Document 1]
U.S. Pat. No. 6,975,377